FIG. 1 is a block diagram of a conventional switch. As shown, the conventional switch 100 includes a plurality of transmission ports 11, via which the switch 100 can perform data transmission with a plurality of calculator nodes 10. Each one of the transmission ports 11 corresponds to a storage unit with specific storage space. Specifically, each one of the transmission ports 11 includes a data receiving storage unit 12 and a data transmitting storage unit 13. The data receiving storage unit 12 and the data transmitting storage unit 13 are configured to store the data packets received by and transmitted to the switch 100, respectively. Generally, each transmission port of a conventional switch has its dedicated storage space; therefore, each one of the storage spaces is designed as large as possible to satisfy various storage statuses of the transmission ports, such as the factors of data packet transmission speed, bandwidth and reading delay, which may affect the use of the storage space. However, not every data packet transmission may use all of the storage space and not all of the transmission ports may transmit data packets simultaneously. Namely, when a conventional switch is in operation, it is possible that only a portion of the transmission ports are being used and another portion of the transmission ports are idled. Therefore, the conventional switch may have resource waste problem due to the idled storage space.